[justajot]

If PoW's costliness is based on production and consumption of energy, it requires a certain amount of energy and natural resources to produce the hardware required to consume the energy, correct?

I'm failing to follow how PoW is fundamentally different than PoST in terms of hardware (and the resources to produce it) necessary to validate blocks.

It seems that the point of PoST is that we get a similar potential of decentralization that we get with PoW with significantly less energy usage.

I somewhat understand the argument of PoW incentivizing production of cheap and clean energy and I hope this is realized ... specifically clean energy, specifically advanced nuclear as its utilization isn't geographically restricted.

[Geee]

Yes, it requires production of mining hardware, but just for adding new hashing capacity to the network. Major part of the mining cost comes from energy, and I believe that in the long run even more so. Energy efficiency of mining hardware has pretty much plateaued, and modern hardware should be good for 10 years of mining, which means that less hardware has to be replaced.

The competition has shifted into finding cheaper energy sources, rather than developing more energy efficient ASICs. There's a clear trend in this direction.